#include <bits/stdc++.h>
using namespace std;
#define _ ios_base::sync_with_stdio(0);cin.tie(0);
#define pii pair<int , int>
#define vi vector<int>
#define pb push_back
#define f first
#define s second
#define ll long long
#define grid vector<vector<int>>
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fll;
const int MAXN = 1e5+10;
int h,w;
grid g;
int isR=0, isF=0, ans=1;
pii moves[] = {{1,0}, {-1,0}, {0,1}, {0,-1}};
bool valid(pii coord, int a){
int x=coord.f, y=coord.s;
return x>=0 and x<h and y>=0 and y<w and g[x][y]==a;
}
void dfs(pii src, int a){
for(pii i : moves){
int x = src.f+i.f, y=src.s+i.s;
if(valid({x,y}, a)) {
if(g[x][y]==1) {
if(isR!=0) g[x][y]=2; else g[x][y]=0;
isF--; isR++;
}
else if(g[x][y]==2){
if(isF!=0) g[x][y]=1; else g[x][y]=0;
isR--; isF++;
}
dfs({x,y}, a);
}
}
}
int main(){ _
cin>>h>>w; g.resize(h, vi(w));
for(int i=0; i<h; i++) for(int j=0; j<w; j++){
char c; cin >>c;
if(c=='.') g[i][j]=0;
else if(c=='F'){ g[i][j]=1; isF++; }
else if(c=='R'){ g[i][j]=2; isR++; }
}
while(isR!=0 and isF!=0){
ans++; dfs({h-1,w-1}, g[h-1][w-1]);
}
cout << ans << endl;
return 0;
}
